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  • 1
    Publication Date: 2019-01-09
    Description: Highlights • Continental margin-scale spatial variability in C values among grain size fractions is presented. • Two different hydrodynamic modes influencing in 14C heterogeneity are identified. • A new index (H14 index) is defined to describe overall 14C heterogeneity within marine surface sedimentary OC. Abstract The deposition and long-term burial of sedimentary organic matter (OM) on continental margins comprises a fundamental component of the global carbon cycle. A key unknown in interpretation of carbon isotope records of sedimentary OM is the extent to which OM accumulating in continental shelf and slope sediments is influenced by dispersal and redistribution processes. Here, we present results from an extensive survey of organic carbon (OC) characteristics of grain size fractions (ranging from 〈20 to 250 μm) retrieved from Chinese marginal sea surface sediments in order to assess the extent to which the abundance and isotope composition of OM in shallow shelf seas is influenced by hydrodynamic processes. Our findings show that contrasting relationships exist between 14C contents of OC and grain size in surface sediments associated with two different hydrodynamic modes, suggesting that transport pathways and mechanisms imparted by the different hydrodynamic conditions exert a strong influence on 14C contents of OM in continental shelf sediments. In deeper regions and erosional areas, we infer that bedload transport exerts the strongest influence on (decreases) OC 14C contents of the coarser fraction, while resuspension processes induce OC 14C depletion of intermediate grain size fractions in shallow inner-shelf settings. We use the inter-fraction spread in 14C values, defined here as 14H , to argue that the hydrodynamic processes amplify overall 14C heterogeneity within corresponding bulk sediment samples. The magnitude and footprint of this heterogeneity carries implications for our understanding of carbon cycling in shallow marginal seas.
    Type: Article , PeerReviewed
    Format: text
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 348-349 (Sept. 2007), p. 517-520 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Crack propagation tests were conducted with CCT specimens made by 2024-T3 Aluminumalloy in benign and corrosive environments to investigate the stochastic characteristics of crackgrowth. A random variable probability crack growth model, base on the modified form of Paris law,was used to characterize the stochastic performance. Distribution significance test has been done,which shows that the random variable X can be considered reasonably to follow log-normaldistribution in all the 4 kind of environments. Variance analysis indicates that the scatter in wet air isgreater than that in laboratory air significantly. Expressions for the probability distribution of cracksize at any given loading cycle and the probability distribution of the random fatigue life at which agiven crack size is reached were discussed. The corresponding calculations for the crack lengthdistribution and P-a-N curves with certain reliability were carried out. The comparisons withexperimental data indicate the validity of the proposed method
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 175-180 
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The problem of multiple site damage (MSD) has got more attention in ageing structures.Cumulative effects of interacting cracks may significantly degrade the damage tolerance capacity ofstructures. Cracks caused by MSD are extremely difficult to detect and greatly reduce the residualstrength, fatigue life and overall structural integrity of aircraft panels. This paper presents a simplenumerical method, which use the principles of fracture mechanics and the computation results, topredict the fatigue crack growth life of MSD structure. Comparing with calculating crack growth lifecycle by cycle, this method will save much time. To verify the validity of the proposed method,experiment was conducted and reported with simulation specimen of representative MSD structurewith 5 details. The comparison between the calculated a-N curves and the crack growth lives and thetest results shows that the prediction result with this fast method is acceptable. A discussion wascarried out by numerical analysis; in with typical MSD structures with different initial crack lengthwere adopted. Crack interaction effect was found obviously, but it occurred mainly in the last part ofthe crack growth lives. The relative size of MSD cracks depends significantly on the distribution ofthe initial cracks
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 348-349 (Sept. 2007), p. 489-492 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This study investigated the residual strength of aluminum alloy sheet with multiple sitedamage (MSD) through three types of aluminum specimens test. Aluminum panels with barecollinear constant diameter holes were chosen as specimens. And there were saw cuts at both edgesof all the holes. After some constant amplitude tension-tension load cycles, the MSD were found inthese specimens since there were multiple fatigue cracks emanating from the saw cuts of holes. Theresidual strength was recorded as the maximum load when every specimen was subjected tomonotonically increasing tensile load until failure occurred. The test results were compared withpredicted residual strength results by five different failure prediction criteria that were often used inengineering in order to evaluate the accuracy of these criteria. The failure criteria included: fracturecriterion, net ligament loss criterion, ligament yield criterion, CTOA/CTOD criterion and averagestress criterion. Ligament yield criterion (Swift criterion) and average stress criterion got moreaccurate prediction results than other criteria
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 324-325 (Nov. 2006), p. 363-366 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The influence of environmental corrosion on fatigue life of 2024-T3 aluminum alloy isinvestigated in this paper. Experiments with center-hole specimens and CC(T) specimens areconducted and reported. The test result shows that the corrosion influence is becoming seriouswhile the environmental causticity is increasing, and the influence on crack initiation life is greaterthan that on crack propagation life. Analysis of the test data also indicates that the environmentalcausticity enlarges the dispersivity of fatigue life. Using the corrosion-modification-factor obtainedby eigenvalue or mean value to prediction the fatigue life with high reliability will cause anunconservative conclusion
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2017-11-17
    Description: Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 120 (2015): 1377–1399, doi:10.1002/2014JB011686.
    Description: Coring/logging data and physical property measurements from International Ocean Discovery Program Expedition 349 are integrated with, and correlated to, reflection seismic data to map seismic sequence boundaries and facies of the central basin and neighboring regions of the South China Sea. First-order sequence boundaries are interpreted, which are Oligocene/Miocene, middle Miocene/late Miocene, Miocene/Pliocene, and Pliocene/Pleistocene boundaries. A characteristic early Pleistocene strong reflector is also identified, which marks the top of extensive carbonate-rich deposition in the southern East and Southwest Subbasins. The fossil spreading ridge and the boundary between the East and Southwest Subbasins acted as major sedimentary barriers, across which seismic facies changes sharply and cannot be easily correlated. The sharp seismic facies change along the Miocene-Pliocene boundary indicates that a dramatic regional tectonostratigraphic event occurred at about 5 Ma, coeval with the onsets of uplift of Taiwan and accelerated subsidence and transgression in the northern margin. The depocenter or the area of the highest sedimentation rate switched from the northern East Subbasin during the Miocene to the Southwest Subbasin and the area close to the fossil ridge in the southern East Subbasin in the Pleistocene. The most active faulting and vertical uplifting now occur in the southern East Subbasin, caused most likely by the active and fastest subduction/obduction in the southern segment of the Manila Trench and the collision between the northeast Palawan and the Luzon arc. Timing of magmatic intrusions and seamounts constrained by seismic stratigraphy in the central basin varies and does not show temporal pulsing in their activities.
    Description: This research is funded by National Science Foundation of China (grants 91428309 and 91028007), Program for New Century Excellent Talents in University, and Research Fund for the Doctoral Program of Higher Education of China (grant 20100072110036).
    Description: 2015-09-16
    Keywords: South China Sea ; Seismic stratigraphy ; Seismic facies ; Neotectonism ; IODP Expedition 349 ; Core-well-seismic integration
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 7
    Publication Date: 2018-02-05
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 9 (2018): 121, doi:10.1038/s41467-017-02504-1.
    Description: Sediments in deep ocean trenches may contain crucial information on past earthquake history and constitute important sites of carbon burial. Here we present 14C data on bulk organic carbon (OC) and its thermal decomposition fractions produced by ramped pyrolysis/oxidation for a core retrieved from the 〉7.5 km-deep Japan Trench. High-resolution 14C measurements, coupled with distinctive thermogram characteristics of OC, reveal hemipelagic sedimentation interrupted by episodic deposition of pre-aged OC in the trench. Low δ13C values and diverse 14C ages of thermal fractions imply that the latter material originates from the adjacent margin, and the co-occurrence of pre-aged OC with intervals corresponding to known earthquake events implies tectonically triggered, gravity-flow-driven supply. We show that 14C ages of thermal fractions can yield valuable chronological constraints on sedimentary sequences. Our findings shed new light on links between tectonically driven sedimentological processes and marine carbon cycling, with implications for carbon dynamics in hadal environments.
    Description: This study is supported by Doc.Mobility Fellowship (P1EZP2_159064) (R.B.) from the Swiss National Science Foundation (SNSF). This work is also supported by SNF “CAPS-LOCK” project 200021_140850 (T.I.E.), by SNSF grant (133481) (M.S.), and Austrian Science Foundation (P 29678-N28) (M.S.).
    Keywords: Carbon cycle ; Sedimentology
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 8
    Publication Date: 2016-12-23
    Description: Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 15 (2014): 4958–4983, doi:10.1002/2014GC005567.
    Description: Combined analyses of deep tow magnetic anomalies and International Ocean Discovery Program Expedition 349 cores show that initial seafloor spreading started around 33 Ma in the northeastern South China Sea (SCS), but varied slightly by 1–2 Myr along the northern continent-ocean boundary (COB). A southward ridge jump of ∼20 km occurred around 23.6 Ma in the East Subbasin; this timing also slightly varied along the ridge and was coeval to the onset of seafloor spreading in the Southwest Subbasin, which propagated for about 400 km southwestward from ∼23.6 to ∼21.5 Ma. The terminal age of seafloor spreading is ∼15 Ma in the East Subbasin and ∼16 Ma in the Southwest Subbasin. The full spreading rate in the East Subbasin varied largely from ∼20 to ∼80 km/Myr, but mostly decreased with time except for the period between ∼26.0 Ma and the ridge jump (∼23.6 Ma), within which the rate was the fastest at ∼70 km/Myr on average. The spreading rates are not correlated, in most cases, to magnetic anomaly amplitudes that reflect basement magnetization contrasts. Shipboard magnetic measurements reveal at least one magnetic reversal in the top 100 m of basaltic layers, in addition to large vertical intensity variations. These complexities are caused by late-stage lava flows that are magnetized in a different polarity from the primary basaltic layer emplaced during the main phase of crustal accretion. Deep tow magnetic modeling also reveals this smearing in basement magnetizations by incorporating a contamination coefficient of 0.5, which partly alleviates the problem of assuming a magnetic blocking model of constant thickness and uniform magnetization. The primary contribution to magnetic anomalies of the SCS is not in the top 100 m of the igneous basement.
    Description: This research is funded by National Science Foundation of China (grant 91028007, grant 91428309), Program for New Century Excellent Talents in University, and Research Fund for the Doctoral Program of Higher Education of China (grant 20100072110036).
    Description: 2015-06-27
    Keywords: Deep tow magnetic survey ; Magnetic anomaly ; Crustal evolution ; Modeling ; International Ocean Discovery Program Expedition 349 ; South China Sea tectonics
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 9
    Publication Date: 2018-10-12
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Geophysical Research Letters 45 (2018): 8425-8434, doi:10.1029/2018GL078904.
    Description: Compound‐specific radiocarbon analysis was performed on different grain‐size fractions of surficial sediments to examine and compare lateral transport times (LTTs) of organic carbon. 14C aging of long‐chain leaf wax fatty acids along two dispersal pathways of fluvially derived material on adjacent continental margins implies LTTs over distances of ~30 to 500 km that range from hundreds to thousands of years. The magnitude of aging differs among grain size fractions. Our finding suggests that LTTs vary both temporally and spatially as a function of the specific properties of different continental shelf settings. Observations suggest that 14C aging is widespread during lateral transport over continental shelves, with hydrodynamic particle sorting inducing age variations among organic components residing in different grain sizes. Consideration of these phenomena is of importance for understanding carbon cycle processes and interpretation on sedimentary records on continental margins.
    Description: National Natural Science Foundation of China Grant Numbers: 41520104009, 41521064; MOE; JSPS Grant Numbers: A‐1003, 2‐1304, B‐0904, B‐0903, 22310014, 23651021, 25550020; NIES; SNSF Grant Number: 200021_140850
    Keywords: Radiocarbon ; Lateral particle transport time ; Organic carbon aging ; Continental shelf sediments ; Grain size fractions
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 10
    Publication Date: 2018-04-28
    Description: The genetic architecture of floral traits in the woody plant Prunus mume The genetic architecture of floral traits in the woody plant 〈i〉Prunus mume〈/i〉, Published online: 27 April 2018; doi:10.1038/s41467-018-04093-z Mei (Prunus mume) is a woody tree that produces ornamental blossoms which symbolize spring in East Asia. Here, Zhang et al. resequence wild and domesticated mei to reveal considerable admixture and introgression from other Prunus species and identify loci associated with floral traits.
    Electronic ISSN: 2041-1723
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General , Physics
    Published by Springer Nature
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